"Could Burst from Bubbling": Concerns Over "5 Million Views" Kimchi Fermenting in Glass Jar by Foreigner

Bubbles Are a Normal Part of Fermentation
Gas Accumulation in Sealed Containers Is Risky
Kimchi Ferments Even at 4°C
Lower Temperatures Significantly Slow the Process

As a video uploaded by a foreigner showing kimchi fermenting in a glass jar has garnered over 5 million views and become a popular topic online, concerns have emerged over the risk of the glass jar breaking due to gases generated during the fermentation process. While the bubbles produced in kimchi are part of the natural fermentation, caution is needed because tightly sealing a container without a gas-release mechanism can lead to significantly increased internal pressure.

Recently, on social media, a user shared a video of homemade kimchi actively fermenting in a glass jar. The creator wrote, “Here is the look and sound of successfully made kimchi after 2.5 days,” and added, “Store-bought kimchi often lacks this fizzy sensation.” As of the 4th, the video had reached approximately 5.3 million views. The creator had previously introduced their homemade kimchi, saying, “Does anyone like kimchi? I make a large batch about once a year.”

A video of a foreigner showing the process of fermenting kimchi filled in a glass jar has surpassed 5 million views and become a hot topic online. However, concerns have arisen that the glass jar may break due to the gas generated during the fermentation of kimchi. Screenshot from SNS

The video particularly drew attention to the constant stream of bubbles rising inside the glass jar filled with kimchi. This led to concern among Korean users, with comments such as “You need to transfer it to a plastic container,” and “If you keep it sealed, one day it could turn into a ‘kimchi grenade.’” The post stirred debate not only in Korea but also on Japanese social media platforms.

In response, the creator countered, “It seems the glass jar is really making people worry,” and explained, “I release the gas every day, sometimes several times a day. This isn’t my first time making kimchi.” They also stated that, depending on ambient temperature, they usually ferment kimchi for an average of 6 to 9 days. When another user questioned the room temperature fermentation method, the creator replied that they ferment the kimchi at approximately 65–70°F (around 18–21°C). They also argued that fermentation stops once kimchi is put in the refrigerator.

If CO₂ Builds Up in a Sealed Container, There Really Is a Risk of Damage... The Glass Jar Itself Isn’t the Problem

So, is the bubbling kimchi in the video a warning sign of danger? First, the bubbles themselves are not necessarily evidence that the kimchi has spoiled. According to the University of Minnesota Extension, during the lactic acid fermentation of vegetables, lactic acid bacteria convert sugars into lactic acid and release carbon dioxide (CO₂), creating bubbles in the fermenting liquid. In other words, the bubbles in the video are a normal part of the kimchi fermentation process. However, concerns among users about the so-called ‘kimchi grenade’ are not entirely without basis.

Food safety guides from Virginia Tech explain that, since fermented vegetables continuously produce carbon dioxide, pressure in a sealed glass jar can become dangerously high if gas accumulates, recommending the use of containers that allow gas to escape. The amount of gas generated during kimchi fermentation has been confirmed in research as well. In a 2023 study published in the journal of the Royal Society in the UK, researchers at the Georgia Institute of Technology observed that when kimchi was fermented in a sealed glass container, its volume increased significantly and carbon dioxide bubbles were formed within a single day.

Since fermented vegetables continuously produce carbon dioxide, pressure inside a sealed glass jar can become dangerously high if gas accumulates. Therefore, it is recommended to use containers that can release gas. Screenshot from SNS

The researchers analyzed that the tiny pores of traditional Onggi earthenware continuously release CO₂ generated during fermentation. Unlike sealed glass containers, Onggi acts as a kind of “manual gas release device.” The Washington Post also introduced this 2023 study, reporting that Onggi’s micro-pores allow carbon dioxide produced during kimchi fermentation to escape into the air.

Plastic Isn’t the Only Safe Option... US College Says Glass May Also Be Used, but Requires an Airlock

The University of Minnesota lists not only plastic and ceramic, but also glass as an acceptable type of food-grade container for home vegetable fermentation. However, it recommends the use of an “airlock” device with glass jars to regulate internal oxygen and carbon dioxide concentrations. Depending on the container, it may also be necessary to slightly open the lid to release accumulated CO₂, a process called “burping.”

Fermented vegetable safety guidelines involving researchers from the US Department of Agriculture (USDA) suggest two methods for kimchi: fermenting for up to two days at about 20°C, or fermenting for three to four days below 5°C. In particular, they emphasize monitoring pH to ensure it reliably drops to below 4.6, rather than setting fermentation time alone, as a core measure for food safety.

This research also cited approximately 18°C as an appropriate fermentation temperature for cabbage-based foods such as kimchi. Therefore, the creator’s stated range of 18–21°C does not indicate an abnormal fermentation temperature. However, the 6–9 days of fermentation described by the creator is much longer than the roughly 20°C time frame mentioned in the guidelines. Ultimately, the actual safety and degree of fermentation depend not just on temperature but also on factors such as salt concentration, hygiene, acidity, and the state of the container.

This content was produced with the assistance of AI translation services.